This application claims the priority of the Japanese Patent Application No. 11-367587 filed on Dec. 24, 1999 and Japanese Patent Application No. 2000-29348 filed on Feb. 7, 2000, which are incorporated herein by reference.
The present invention relates to an external preparation for skin including an extract from a particular plant, and more particularly, to an improvement of anti-aging effect and whitening effect thereof.
Generally, the external preparations for skin such as milky lotions, creams, lotions, packs, detergents, dispersion solutions, ointments, liquids for external use are including various active ingredients, to perform specified drug effect.
For example, external preparations for whitening include whitening ingredients of ascorbic acid, glutathione and hydroquinon etc., to prevent phenomenon of darkening caused by sunburn, brown spot and freckle etc. caused by pigmentation.
Also, cell activation agents of vitamin A, soybean extract and seaweed extract etc. are compounded in the external preparation for skin for the purpose of an anti-aging effect, to improve wrinkle, slack of skin caused by aging, ultraviolet rays exposure etc.
However, in the prior arts, the effects of the component for whitening or anti-aging were not sufficient. And, these components may be degraded in pharmaceutical preparation. Because of this, these conventional components are not sufficient to demonstrate desired drug effect. Therefore, improvements of these and new active ingredients have been desired.
The object of the invention is to provide better whitening or anti-aging effect by a high safety plant extract.
The present inventors have been conducted a search for natural components that have excellent drug effect and can use as an active ingredient of external preparation for skin, and found an extract from Pueraria mirifica, that is a plant in Southeast Asia, has high melanine formation inhibition and also anti-aging effect. Furthermore, the extract is effective when it is compounded in external preparation for skin as a whitening component or an anti-aging component. Also, excellent effects are obtained when other active ingredients are compounded with the extract. The inventors have completed the invention based on this finding.
Namely, an external preparation for skin according to the present invention includes an extract of Pueraria mirifica. 
Also, in said external preparation for skin, the extract of Pueraria mirifica is preferably compounded as a whitening component.
Also, an external preparation for whitening according to the present invention comprises;
(A) extract of Pueraria mirifica; 
(B) one or more active ingredient selected from the group consisting of a whitening agents, an anti-oxidant, an anti-inflammation agent and an ultraviolet-ray shielding ingredient.
Also, in said external preparation for skin, the extract of Pueraria mirifica is preferably compounded as an anti-aging component.
Also an external preparation for anti-aging according to the present invention includes the followings;
(A) the extract of Pueraria mirifica; 
(B) one or more effective ingredient selected from the group consisting of a cell activation agent, an anti-oxidant, a humectant, and an ultraviolet-ray shielding ingredient.
Pueraria mirifica, of which extract is used as an active ingredient in the invention, is a plant grows in Southeast Asia. The plant belongs to Legume lobata and called Kwaao Khruea in Thailand. Pueraria mirifica includes various isoflavone derivatives that have female hormone effect. Therefore, it has been used as a Thailand medicine, private spice, herb, traditional medicine etc. heretofore.
The extract of the above plant used for the invention is obtained by extracting a dried root lump of said plant by using a proper extraction solvent. The method for preparation is not restricted but especially prepared by extracting under low temperature or room temperature to warming by using a proper solvent.
As for extraction solvent used in the invention, examples are as follows;
water; lower alcohol such as methyl alcohol, ethyl alcohol; liquid polyhydric alcohol such as glycerol, propylene glycol, 1,3-butylene glycol. One or more of these can be used for the extraction solvents.
Also, the example of the preferable extraction method is as follows. The extraction from Pueraria mirifica is carried out for 1 to 5 days with room temperature by 0xcx9c100 v/v % water content ethyl alcohol or 1,3-butylene glycol. This extract is filtered. The filtrate thus obtained was allowed for around 1 week for aging. The result was filtered again.
The compounding quantity of Pueraria mirifica extract in the external preparation for skin of this invention is preferably 0.00001xcx9c5 wt % (hereinafter indicated xe2x80x9c%xe2x80x9d only) as the dried solid in the composition. In the case where it is used as a whitening component, the compounding amount is more preferably 0.03xcx9c2%. In the case where it is used as an anti-aging component, the compounding amount is more preferably 0.0001xcx9c2%. Said plant extract can be stably compounded in this range and show a high effect. In the case where the extract is used as liquid, as long as the content of the dried solid in extract is in above range in the external preparation, the concentration is not restricted.
The Pueraria mirifica extract of this invention can be compounded with the various bases of usual external preparation for skin in accordance with common methods. The external preparation for skin can show excellent effect, by compounding with other active ingredients.
As for the active ingredients ((B) component) in combination with the Pueraria mirifica extract ((A) component), examples are as follows. In the case of a whitening use, the active ingredients may be other whitening agents, anti-oxidants, antiinflammation agents, ultraviolet-ray shielding ingredients etc. In the case of an anti-aging use, the active ingredient is a cell activation agent, anti-oxidants, humectants, ultraviolet-ray shielding ingredients etc. These concrete active ingredients are shown below, respectively.
Whitening Agent
As for whitening agent used in the invention, examples are as follows; vitamin C, its derivatives and salts thereof, placenta extract, licorice extract, coix seed extract, scutellaria root extract, seaweed extract etc. The whitening agents are not restricted as long as which has a whitening effect. In these whitening agents, vitamin C, its derivatives and salts thereof, and placenta extracts are preferable.
Anti-Oxidant
As for anti-oxidant used in the invention, examples are as follows; vitamins B, its derivatives and salts thereof, vitamin E, its derivatives and salts thereof, dibutylhydroxytoluene, dibutyl hydroxyanisol, mannitol, carotenoid such as astaxanthine, plant extract including flavonoid such as quercetin, quercitrin, ginkgo extract, scutellaria root extract, balm mint extract, saxifrage extract, Siberian ginseng extract, and Alnus firma Siebold. et Zucc. extract. In these anti-oxidant, vitamin E, its derivatives and salts thereof are preferable.
Anti-Inflammation Agent
As for anti-inflammation agent used in the invention, examples are as follows; glycyrrhizinic acid, glycyrrhetinic acid, those derivatives and those salts, aloe extract, perilla extract, mugwort extract and matricaria extract. In these anti-inflammation agents, glycyrrhizinic acid, glycyrrhetinic acid, those derivatives and those salts are preferable.
Ultraviolet-Ray Shielding Agent
As for ultraviolet-rays shielding agent used in the invention, examples are as follows; 2-ethylhexyl-p-methoxy cinnamate, oxybenzone, 4-tert-butyl-4xe2x80x2-methoxy dibenzoylmethane, titanium oxide, micronized particle titanium oxide, and zinc oxide. In these ultraviolet-ray shielding ingredients, 2-ethylhexyl-p-methoxy cinnamate, titanium oxide, micronized particle titanium oxide and zinc oxide are preferable.
Cell Activation Agent
As for cell activation agent used in the invention, examples are as follows; vitamin A, its derivatives and those salts, vitamin C, its derivatives and those salts, estradiol, placenta extract, yeast extract, apricot extract, plant extract including AHA such as lime extract and raspberry extract, asparagus extract, almond extract, soybean extract, centella extract, tomato extract, malt root extract and seaweed extract. In these cell activation agents, vitamin A, its derivatives and those salts, and estradiol are preferable.
Humectant
As for humectant used in the invention, examples are as follows; amino acid, its derivatives and those salts, mucopolysaccharide, its derivatives and those salts, phospholipid and its derivatives, sweet hydrangea leaf extract, aloe extract, cactus extract, coltsfoot extract, quince seed extract, glycerol, and 1,3-butylene glycol. In these humectant, amino acid, its derivatives and those salts, phospholipid and its derivatives, glycerol and 1,3-butylene glycol etc. are preferable.
The compounding amount of the active ingredient of above (B) component in the external preparation for skin of this invention differs depend on the kind of active ingredient. However, the compounding amount is preferably in the range shown below. In the case of compounding the active ingredients with the extract of Pueraria mirifica as (A) component in the range, it does not influence on stability with time and shows higher whitening effect and anti-aging effect.
In the case of the external preparation for whitening of this invention, other whitening agents as (B) component can be compounded in an amount of 0.00001xcx9c10%, preferably 0.0001xcx9c5% in the composition. In the case of using the placenta extract or various plant extracts in liquid, the compounding amount should be in the range as dried solid. This range shows excellent whitening effect and fine feel of use.
In the case of the whitening external preparation of this invention, the anti-inflammation agent as (B) component can be compounded in an amount of 0.00001xcx9c5%, preferably 0.0001xcx9c3% in the composition. In the case of using various plant extracts in liquid, the compounding amount should be in the range as dried solid. This range shows an excellent antiinflammation effect and excellent whitening effect.
In the case of the anti-aging external preparation for skin of the invention, the cell activation agent as (B) component can be compounded in an amount of 0.00001xcx9c10%, preferably 0.0001xcx9c5% in the composition. In the case of using the placenta extract or various plant extracts in liquid, the compounding amount should be in the range as dried solid. This range shows excellent cell activation effect and excellent antiaging effect.
In the case of the anti-aging external preparation of this invention, the humectants as (B) component can be compounded in an amount of 0.00001xcx9c5%, preferably 0.0001xcx9c3% in the composition. In the case of using various plant extracts in liquid, the compounding amount should be in the range as a dried solid. This range shows excellent moisturizing effect and excellent anti-aging effect.
Also, in the case of either of the external preparations of this invention, the anti-oxidants as (B) component can be compounded in an amount of 0.00001xcx9c5%, preferably 0.0001xcx9c3% in the composition. In the case of using various plant extracts in liquid, the compounding amount should be in the range as dried solid. This range shows excellent anti-oxidant effect, excellent anti-aging effect and whitening effect.
Also, in the case of either of the external preparations of this invention, the ultraviolet-ray shielding agents as (B) component can be compounded in an amount of 0.0001xcx9c20%, preferably 0.001xcx9c10% in the composition. This range shows excellent ultraviolet-ray shielding effect, excellent anti-aging effect and whitening effect.
One or more of various kinds of (B) component can be combined to use.
The external preparation for skin including above (A) component and (B) component can be prepared in accordance with a common method. Namely, (A) component and (B) component are compounded in the bases of various state which can be used in usual external preparation for skin.
As for concrete product in connection with the external preparation for skin of the invention, examples are as follows. Cosmetics and medical external preparation such as a milky lotion, cream, lotion, pack, detergent, makeup cosmetic, dispersion solution and ointment.
The external preparation for skin of this invention can include components, that are usually used in the external preparation for skin such as the cosmetics and medical external preparation, other than the above indispensable components. Followings are examples; purified water, lower alcohol, polyhydric alcohol, oily components, powders, surface active agents, thickeners, color materials, antiseptics, humectants and perfume etc.